Objective To describe the criteria used to guide clinical decision-making regarding when a patient is ready to return to running (RTR) after ACL reconstruction. Design Scoping review. Data sources The MEDLINE (PubMed), EMBASE, Web of Science, PEDro, SPORT Discus and Cochrane Library electronic databases. We also screened the reference lists of included studies and conducted forward citation tracking. Eligibility criteria for selecting studies Reported at least one criterion for permitting adult patients with primary ACL reconstruction to commence running postoperatively. Results 201 studies fulfilled the inclusion criteria and reported 205 time-based criteria for RTR. The median time from when RTR was permitted was 12 postoperative weeks (IQR=3.3, range 5-39 weeks). Fewer than one in five studies used additional clinical, strength or performance-based criteria for decision-making regarding RTR. Aside from time, the most frequently reported criteria for RTR were: full knee range of motion or amp;gt;95% of the non-injured knee plus no pain or pain amp;lt;2 on visual analogue scale; isometric extensor limb symmetry index (LSI)amp;gt; 70% plus extensor and flexor LSIamp;gt; 70%; and hop test LSIamp;gt; 70%. Conclusions Fewer than one in five studies reported clinical, strength or performance-based criteria for RTR even though best evidence recommends performance-based criteria combined with time-based criteria to commence running activities following ACL reconstruction.